It is essential that a piano keyboard play well--"feel" very good to the musician. He is highly interested in touch, balance, inertia, etc.
With regard to touch, it is emphasized that different pianists have different requirements in that some like it light and others heavy. To achieve--at almost no added cost--a piano whose touch may be changed in a manner of minutes by a dealer, in order to satisfy a particular buyer, is a distinct accomplishment.